Having read the DIY on plugging up the symposer tube ( from the inside) to get a quieter cabin, I tried it and after a few days decided to unplug it and revert to normal. Reason being the exhaust sound became intrusive with a noticeable 'booming' under acceleration. I am guessing that the sound symposer was designed not only to pipe the 'pleasant' intake noise to the cabin but also to mask the resonance in the PSE exhaust. Am I right?

 

I think we all have our own interpretations of "booming" but I have my symposer plugged and like the exhaust sound instead of the piped intake noise. However, when my change over valve failed in the exhaust, the resulting exhaust noise was really annoying at medium revs and could best be described as "booming".
Maybe have the service center check your change over valves?

 

Yes it is difficult to describe the booming sound but it was annoyingly harsh and ringing ( to my ears at least). If by change over valve you mean the PSE bypass valve I think it is working fine because there is a big difference in the exhaust sound when the button is activated. Nevertheless I will have it checked at next service. Thanks.

 

I happen to like the sound inside the car. I have an S with PSE and still like the sound of the exhaust inside as well as outside when the windows are down.

 

Same here! I find myself turning the stereo off most of the time. If wanting a quiet interior, turning off PSE makes the car sound like a kitten. Turn it on, and the lion comes out.

Not sure why anyone would mess with the symposer? PSE on and not wanting to hear it?

 

I have an S with PSE and still like the sound of the exhaust inside as well as outside when the windows are down.

 

I believe that the reference to the COV has nothing to do with the PSE bypass valve. The COV opens and closes based on the vacuum from the engine. The more vacuum created,the more volume to the symposer. If the COV has failed, the effect will be a quieter cabin with the PSE off. I noticed that my exhaust COV failed about 1,000 miles ago and I prefer to leave it inop. It is simpler fix than plugging the symposer. I prefer to hear the natural sound of my AWE performance exhaust, which used to be masked by the symposer. Hope this helps. If you want to learn more about the COV's in the P-car, search it and you will understand how they work and what they effect, not to mention the continuing trouble folks are having with the ones in the 2012, 2013 and some 2014 cars.

 

I wrote one of the DIY writeups for the symposer mod. IIRC, the drone and the interior noise were reduced, not exaggerated.

That said, I do agree with most of the comments -- that I enjoyed the interior noise with the symposer. I simply performed the mod to see how the interior sound would change.

Now that I have the x-pipe, none of it really matters!

 

Just to clarify -- in my case, the symposer COV was fine, but my exhaust COV (non-PSE) failed, causing the annoying drone.

 

I'm in the other camp. I plugged my symposer and enjoy the solitude of the quiet cabin most of the time. But I equally enjoy hitting my LOUD button from time to time. Nice to have choices!

 

fbroen/ 911carreradriver/christophosphorus. Am a bit confused now. Do you mean 1. If symposer COV fails then you get a quieter cabin because no intake sound will be piped in,
and 2. If a PSE COV fails then exhaust sound will be as if you have pressed the LOUD button?

 

What you're asking depends on the actual valve position upon failure (if I'm completely wrong, someone stop me).

My comments were about the symposer valve. From my experience, plugging the valve pipe makes the car QUIETER because the additional engine/intake noise is blocked, and does not enter the cabin as much as it previously did. Mind you, this is mainly apparent when Sport mode is enabled (and the valves open).

If I'm correct in my assumptions, the valve can fail either in the open or closed position. So, if your PSE COV fails and the valve was open, you will not be able to close the valve, and you'll have a loud exhaust the entire time. Same with the symposer; if the COV fails while it's in the open position, then you won't be able to close it, resulting in more induction noise all the time.

The only other way I can see this going is if valve failure results in an always-on position for either one.

Am...am I right?